1. Field of the Invention
The embodiments of the present invention relate to a writing instrument such as an ink pen. For example, the writing instrument may include: a hollow body, typically tubular, extending between a rear end and a front end; a writing member mounted inside the body and provided with a tip at a free end; a protective sleeve movable between a tip protection position (position in which a protective end of the sleeve extends towards the front of the body, completely covering the tip) and a retracted position for writing (position in which the tip protrudes towards the front from the protective sleeve through an opening); at least one first stop formed on the body; and at least one locking member able to engage the first stop in order to maintain the protective sleeve in one of its two positions.
2. Description of Related Art
A writing instrument of the type mentioned above eliminates the use of a detachable cap that can be lost, while providing protection for the writing tip. For example, document FR 2,103,492 describes a writing instrument having a protective sleeve with a substantially conical front end and in which the retracted position for writing is maintained by the introduction of a locking protrusion within a recess or groove formed on the outer face of the tubular body. This type of protective sleeve has a spring clip provided with a ridged area to allow the user to push the protective sleeve rearward into the retracted position for writing, where the locking member engages. The elasticity of the spring clip allows raising the protective sleeve then pushing it forward to return to the protection position.
For this type of operation, a thinning of the release clip (reduced thickness at the clip connection) is required in order for it to be flexible, which increases the risk of clip breakage. In addition, it can be more difficult to hold the writing instrument because of the presence of the release clip.